Method of manufacturing tetra-alkylated thiuramdisulphides



Patented Nov. 18, 1930 UNITED STATES PATENT o IcE HAROLD s. ADAMS, orLAncHivron'r, new YORK, nn LUDWIG'MEUSER, or Boom)" BROOK, NEWJERSEY,Assieivonsmo Tris NAUGATUCK CHEMICAL COMPANY, 'OF NAUGATUCK,CONNECTICUT, A conroiari'rion or. CONNECTICUT METHOD OEMANUFACTURENG TErRaALK LATED THI nAMDISULPHIDES No Drawing.

When a di-alkyl dithiocarbamate isoxi dized to a thiuramdisulphidevby-treatment w th a halogen-or other oxidizing agent, two

molecules of amine are simultaneously-liberated. If the reaction becarried out with pure materials, the liberated amine will naturally be asecondary amine. It the-reaction is carried out by treating'a mixture ofprimary, secondary and tertiary amines with carbon disulphide, tion maybe composed partially of secondary amine but where considerable tertiaryamine v is present, the tertiary amine will remain as free amine. Whenoxidizing agents other than halogens are used, the amine or amlnesliberated or not reacted upon during the oxidation'are liable tooxidation, with .the resultthat the amineisfdestroyed and at. the sametime a portion of the oxidizing agent is also used up; This leads toeconomical. difficulties and low yields of thiuramdisulphide .based uponthe amount of amine originally employed. By maintainingthe reactionmixture at a low temperature, say (3., the

amines liberated ornotreacted with are less.

liable to oxidation. If the oxidizing agentbe introduced very slowly,the extent of oxidation of the amines may bereduced, but even so thereis still a considerable loss of valuable.

raw materials. v v o I o I The present inventionrelatesf primarily tomethods of protecting from oxidation the amines liberated in the courseof theoxidation of dithiocarbamates to form disulphides. 7

Another obj ect of the inventionis to provide an I improved 'method' formanufacturing tetra-alkylated'thiuramdisulphides. A further object is tooxidize dithiocarbamates undersuch conditions that free amines injthereaction mixtureare not destroyed. Another objectoi the invention is toprovide animprovedand economical method for manufac turing tetraalkylated thiuramdisulphides by carrying out the oxidation of suitabledithiocarbamates With anoxidizing agent in the presenceof a reagentadapted toiorm'a ful raw material wlth the amines liberated during, ornot entering, the r'eaot'ion of oxidation. Another object is to carryoutthe oxidation otsuitable dithiocarbamates to corthe'amine liberated uponoxida use- Applicaticnfiled August 4, 1925. Serial No. 48,669.

esponding thiuramdisulphides with a nonhalogen oxidizing agent in thepresence of an inorganic acid. I I VVith' a preferred method in mind,but without desiring to place undue limitations upon the scope of theinvention beyond What may be required by the prior art, the inventionconsists in'treating a secondary amine or mixture of amines containingsecondary amine with carbon bisulphide to form the correspondingdithio'carbamate, oxidizing the dithiocarbamate with a non-halogenoxidizing agent in the presence of a reagent adapted to protect theliberated amine from oxidation, and continuing the several reactionsuntil substantially all of the secondary amine has been converted intothiuramdisuhohide.

Morespeciiically, the invention consists in carrying out the oxidationof the dithiocarbamate of a secondary amine to a thiuramdisulphide bymeans of hydrogen peroxide in the presence of sulphuric acid. Theinvention alsoincludes carrying out such oxidation processfinthepresence of an excess of carbon 'disulphide, orvby theaddition ofcarbon bisulphide insuch a manner as to cause substantially all of thesecondary amine present to become converted into tetra alkylatedthiuramdisulphide.

i The salts of amines, particularly the amine salts of strong acids, aremuch less susceptible to oxidation than the free amines themselves. Thepresent invention therefore aims to prepare such amine salts durlng thecourse of the reaction, as the amines are liberated, and therebyto'prot-ect the amines againstoxidation and loss, both of amines and ofoxidizing agent." When halogen oxidizing agents are used, this 'is'accomplished automatically, for the halogen in'the presence of watergives rise ,to a halogen acid. However, the halogen oxidizing agents areexpensive,

cause undesirable side reactions, and have other disadvantages. Hydrogenperoxide is a satisfactory oxidizing agent, but does not automaticallyneutralize and thus protect the amines which it liberates during theoxidation of a dithiocarbamate into a. thiuramdi- If an equivalentamount ofa suitsulphide.

suchas hydrochloric acid or-sulable acid,

R,Nn+1no, 3 solution) 00, mmnamsowmoaaa, solution) No reaction Theoxidizing agent is most conveniently prepared by diluting 98% sulphuricacid to a convenient strength such as 1030% and cooling thoroughlybefore adding hydrogen peroxide thereto. This. avoids the rise oftemperature which would occur were the acid added to the peroxide, ortheperoxide added to the concentrated; acid.

As an illustration of the invention as applied to substantially puredimethyl amine,

the following is given: A water solution containing 180 lbs. ofdimethylamine is caused to react with 152 lbs. of carbon disulphide. Thealkyl dithiocarbamate thus formed is then oxidized totetramethylthiuramdisulphide byadding with stirring and cooling, 453lbs. of 7 hydrogen peroxide to which has "been added l03 lbs. of 98%sulphuric acid with suitable dilution as indicated above. Thetetramethylthiuramdisulphide formed "by the oxidation may thenbefiltered out, avashed and dried. Approximately of the dimethylamine"appears as tetramethylthiuramdisulphide; But the remainder of the amine,which is liberated during tllGOXllltion reaction, has becomeautomatically combined with the sulphuric acid to form. dimethylaminesulphate. This dimethylamine sulphate remains in thefiltrate and isrecoverable. If desired. the filtrate containing the lbs. ofdimethylamine as sulphate may be treated with 85 lbs. of sodiumhydroxide or the equivalent amount of another alkali and liberated asthe tree amine. The free amine may be distilled oil and absorbed inwater and used again. Another convenient method of handling thedimethylamine sulphate is to free it by treatment with an alkalihydroide and cause the tree amine to react with additional carbonbisulphide to form dithiocarbamate, and repeating the oxidation as setforth in the above example. This may be continued until practically allof the dimethylamine has been converted intotetramethylthiuramdisulphide. Towards the latter stages tertiary amineor another base may be introduced.

While dimethylamine has been given as an example, it is of courseunderstood that other secondary amines may be employed with equalfacility. The invention may also be practiced upon a mixture of primary,secondary and tertiary amines or of primary and secondary amines orofsecondary and tertiary amines or secondary amines and bases in solutionwhich are not affected by the carbon disulphide or the oxidationreactions. The claims are understood as comprehending secondary amine ora mixture containing secondary amine.

As anexample of carrying, out the invention with a mixture of amines,the following may be given: A water solution ofdimethylamine,trimethylamine and methylamine, containing in total 19.3lbs. of nitrogen, may be treated with 52.4 lbs. of carbon bisulphide.The primary and secondary amines are converted into the correspondingdithiocarbamates while the tertiary amine is not changed.

To the reaction mixture, with stirring and cooling, 156 lbs. of a 7.5%solution of hydrogen peroxide containing 34.6 lbs. of 98% sulphuric acidare added. The secondary amine is converted into the correspondingtetraalkylated thiuramdisulphide, the primary amine into thecorresponding mustard oil, and'the tertiary'amine remains in solution assulphate. The thiuramdisulphide is then filtered out, freed from themustard oil, washed. and dried.

The invention may also be carried out by treating dimethylamine or othersecondary amine with an excess of carbon bisulphide, either by startingwith an excess of the carbon bisulphide,but preferably adding thenecessary excess after the oxidation. Awater solution containing 90 lbs.of dimethyl amine may be treated with 76 lbs. of carbon bisulphide. Theamine is converted into the corresponding dithiocarbamate which is thenoxidized by treatment with l53 lbs. of a 7.5% solution of hydrogenperoxide, the latter being run in slowly with stirring and cooling. Atthe same time an additional 6 lbs. of

carbon bisulphide may be run in at such rate it that the total amount ofcarbon bisulphide is added in approximately the same time as thatrequired for the addition'of the total amount of hydrogen peroxide. Thetetramethylthiuramdisulphide thus formed may be filtered out, washed anddried. The simultaneous formation of dithiocarbamate from thedimethylamine liberated during the OXlda- Q' tion reaction, and theoxidation of thedithim carbamate to the corresponding tetramethyl jthiuramdisulphide may be continueduntil approximately all of thedimethyl aminehas been converted.

Having thus described our invention wha we claim and desire to protectby Letters Pat entis: 1 I f 1. A process for making tetra alkylatedthiuramdisulphides which comprises treating.

a secondary amine with an excess ofcarbon disulphide, oxidizing thedithiocarbamate thus formed to a thiuramdisulphide and causing theliberated secondary amine to react With the excess carbon disulphide toform additional 'dithiocarbamate, oxidizing the dithiocarbamate as itforms into further thiuramdisulphide and recovering thethiuramdisulphide from the reaction mixture.

2. A process for making tetramethylthiur amdisulphide which comprisestreating dimethylamine With an excess of carbonjdisulphide, oxidizingthe alkyl dithiocarbamate thus formed to tetramethylthiuramdisulphideand continuously causing the liberated dimethylamine to be convertedintoadditional 1 alkyl dithiocarbamate byreaction with the excess carbondisulphide and then oxidized to tetramethylthiuramdisulphide untilsubstans tially all the dimethylamine has been con verted, andrecovering tetramethylthiuramdisulphide from the reaction mixture.

3. A process for making tetramethylthiuri amdisulphide which comprisestreating .di-

'methylamine with carbon disulphide, oxidizo I ing the alkyldithiocarbamate thus formed to tetrainethylthiuramdisulphide with hydro-1 gen peroxide and simultaneously causing the liberated dimethylamine tobe converted into additional alkyldithiocarbamate by the addition ofexcess carbon disulphide and oxidized to tetramethylthiuramdisulphideuntil sub,-

stantially all the dimethylamine has been con sugmide from thereaction-mixture.

igned at New York, county of New York, 1

and State 'of New York, this 31st day of July,

, Signed. at Naugatuck, county of New Haven, State of Connecticut, this30th day of July,

-LUDWIG MEUSER. i i

HAROLD s. ADAMs m 1

